The Gynecologic Oncology Group (GOG) is the foremost multi-disciplinary cooperative clinical trial research group devoted to the study of gynecologic malignancies. Since its inception in 1970, the GOG has been a recognized leader in the development of new forms of treatment and has relied on the phase III trial as the design to identify new information. Supporting that major activity are the concerted efforts of modality committees providing recent approaches and procedures in each of the relevant diagnostic and therapeutic disciplines. The GOG has an active, effective program in the study of new chemotherapeutic agents in gynecologic cancers and this program has introduced important findings for study in the Phase III setting. In patients with advanced cervical, endometrial and ovarian cancers, the GOG has defined significant improvement associated with the use of cisplatin. The GOG has performed a series of trials to examine the role of paclitaxel either as a single agent or in combination with other agents. Isofamide was found to be one of the most active single agents in squamous carcinoma of the cervix. The results of Phase III studies by the GOG have provided a new standard of treatment in suboptimal ovarian cancer using platin and taxol. Two recently completed trials of post-operative patients with intermediate risk endometrial and cervical cancer showed a significant improvement with adjuvant radiotherapy. The benefit of post-operative adjuvant chemotherapy has been confirmed for patients with totally resected, early stage ovarian cancer. In addition, the GOG has been active in developing new mechanisms to enhance translational research, cancer prevention and control and medical informatics. The Group has collaborative actively with the NCI in evaluating new data management collection and reporting systems. After more than 25 years, the GOG continues to be foremost in developing new strategies in the management of these cancers.